Field of the Invention
Embodiments of the present invention generally relate to shuttle valves.
Description of the Related Art
In hydrocarbon exploration and production, blowout preventers (BOPS) are used to seal a fluid path in the event of an emergency, such as an overpressure condition in the well bore which could, if not controlled, lead to a discharge of well fluids or a “blowout” condition. Blowout preventers typically use opposed hydraulically powered rams to contact and close a drill or production pipe in a blowout event. Each ram is a fluid filled cylinder with a piston face on one side thereof and a rod on the other side. When the rams are actuated, fluid on the piston side thereof is pressurized and the rod (ram) is driven out of the cylinder and into contact with the pipe. Reverse operation causes the rams to retract. The rams can be shaped so that the rod portions coming from either side of the pipe have a cutout conforming to the pipe, can be flat to be used when no pipe is present, or have knife like cutting surfaces to cut through the pipe and close off the well bore.
Fluid power circuits for actuating the rams are necessarily redundant and spring biased shuttle valves are effective for ensuring an alternative fluid path through the valve to the hydraulically operated device, such as the blowout preventer. In most instances, the valves are “stacked” to provide a plurality of redundant fluid pressure sources to the BOP, and thus provide redundancy in case of a failure of a particular valve or its pressurized fluid source.
Current stacked shuttle valve designs are not easily re-configurable and must be:
1) wholly replaced when a shuttle stage needs to be added or removed, or
2) wholly dismantled when an individual shuttle or component related thereto needs to be added or removed.
fully dismantled prior to the servicing thereof in the field.
processed to include coined seal elements after assembly in order to achieve a leak tight metal to metal adapter seal.
configured with a large spring biased shuttle valve adapter assembly in order to provide the spring bias functionality.
Additionally, the components of current stacked shuttle valves cannot be used in single shuttle valve assemblies.
Due to the increased depth of BOP installations in current subsea drilling operations, and changes in regulatory requirements which can require re-configuration of stacked shuttle valves and increased flow rates, prior art shuttle valve stacks no longer meet expected long term industry requirements.
There is a need in the industry for a shuttle valve stack arrangement that is designed to be fully serviced and reconfigurable in the field. This is a further need to significantly reduce stacked shuttle valve down time for repair, improve reliability of stacked shuttle valves and enable an end user to reconfigure stacked shuttle valves when required without the need to return them to the manufacturer.
There is a further need in the industry for a re-configurable pressure and spring biased shuttle valve that has the flow rate capacity needed for normal BOP ram operation and the specific BOP ram stroking, i.e., “closing”, time limit required by industry and regulations.